残余应力超声无损检测与调控技术研究

发布时间：2018-09-08 17:03

【摘要】：残余应力对机械构件的服役性能具有重大影响,尤其是对其强度、疲劳寿命和尺寸稳定性。如何快速、无损地检测与调控构件表面或一定深度内的残余应力一直是研究难点和热点问题。为了解决这一问题,本文首先对残余应力的声弹性检测、残余应力的高能超声调控进行了理论研究与仿真模拟。而后制定了残余应力检测与调控系统的技术指标与构成,建立了残余应力超声检测与高能超声调控的软硬件系统,其中主要提出了声时差优化算法,创新地将检测与调控系统结合,首次开发出高能超声调控状态下的残余应力在线实时监测系统,初步实现了残余应力检测与调控的闭环控制。进一步,考虑到工程现场的环境因素对检测精度的影响,研究了残余应力检测系统的标定与校准方法、残余应力检测的补偿理论与方法,通过与X射线残余应力分析仪的对比试验,以及不确定度分析等,验证了检测精度达到设计要求;在调控方面,通过三因素三水平的正交试验,研究了各影响因素对不同材料残余应力的调控规律,得到最佳调控参数。最后针对几种典型材料典型工程装备,利用自研的残余应力检测与调控系统,开展了服役状态下残余应力超声检测与原位局部调控的应用研究。第一章阐述了论文研究的目的和意义,对国内外残余应力无损检测技术、残余应力调控技术的最新现状进行了综述和对比分析,概述了全文的研究内容。第二章基于声弹性理论,研究了超声波传播速度和方向与应力的关系,对比研究了纵波、表面波和剪切波对应力的敏感度。基于斯涅耳定律,产生出沿着被测件表面传播的临界折射纵波,利用固定声程的声时法,推导了应力系数K的表达式,给出了应力系数与传播声程的理论关系。研究临界折射纵波的传播规律,并对传播过程进行有限元仿真分析。基于超声频率与渗透深度的关系,建立了应力深度梯度检测的理论模型,设计了C形应力试样来产生应力梯度,通过对比X射线应力分析仪测量值与C形试样应力仿真值,验证了模型的正确性。第三章对残余应力高能超声调控理论进行了研究。从两个方面阐释了高能超声调控残余应力的机理。一是研究了高能超声对位错的微观作用,建立了高能超声对晶格位错松弛作用的数学表达式;二是分析了高能超声对材料的宏观塑性诱导效应,通过塑性诱导仿真与实验,证实了高能超声能降低材料的屈服强度,激活错排原子,加快残余应力的消减过程。第四章开发与建立了残余应力超声检测与调控的软硬件系统。对声时差测量的不同算法组合进行了Matlab仿真,考虑了耦合剂薄膜厚度不均,以及被测件厚度不同带来的误差,提出了声时差优化算法。创新地将检测与调控系统结合,通过设计ZTC4钛合金的应力闭环调控实验,初步实现了残余应力检测与调控的闭环控制。第五章在残余应力声弹性检测原理基础上,提出了检测系统的标定与校准方法,着重开展了残余应力检测的补偿理论与方法研究。建立了温度对检测精度影响的理论模型,提出了温度补偿算法并试验验证;研究了晶体粒度和形态分布对检测精度的影响,提出了理论计算补偿法和拉伸试验补偿法并试验验证;对被测件表面弧度与粗糙度的影响进行分析,提出有效解决途径。通过对现场检测结果的不确定度分析,证实了系统的检测精度。在残余应力超声调控原理基础上,采用三种典型材料,研究了各因素对不同材料应力调控的影响规律,得到最佳调控参数。同时还研究了高能超声对材料硬度、强度和金相组织的影响,验证了残余应力高能超声调控理论。第六章利用研发的残余应力超声检测与调控系统,开展了针对铝合金焊接与铆接件、结构钢焊接件以及非金属件的残余应力检测与调控工程应用研究。根据现场应用的经验与效果,分别制定了检测工艺规范与调控工艺规范。
[Abstract]:Residual stress has a great influence on the serviceability of mechanical components, especially on their strength, fatigue life and dimensional stability. How to detect and control the residual stress on the surface or in a certain depth quickly and nondestructively has always been a difficult and hot issue. After that, the technical index and composition of the residual stress detection and control system are formulated, and the software and hardware systems of the residual stress detection and high-energy ultrasonic control are established, in which the acoustic time difference optimization algorithm is proposed, and the detection and control system is innovatively designed. The on-line real-time monitoring system of residual stress under the condition of high-energy ultrasonic control is developed for the first time, and the closed-loop control of residual stress detection and control is preliminarily realized. Compensation theory and method, through the comparative test with X-ray residual stress analyzer, and uncertainty analysis, verify that the detection accuracy meets the design requirements; in the control aspect, through three factors and three levels of orthogonal test, study the regulation rules of various factors on the residual stress of different materials, and get the best control parameters. Aiming at several typical engineering equipments made of several typical materials, the application research of ultrasonic testing and in-situ local control of residual stress in service state is carried out by using the self-developed residual stress detection and control system. Chapter 1 expounds the purpose and significance of the research, and the most important of the non-destructive testing technology of residual stress at home and abroad, and the residual stress control technology. In the second chapter, based on the theory of acoustic elasticity, the relationship between ultrasonic propagation velocity, direction and stress is studied, and the sensitivity of longitudinal wave, surface wave and shear wave to stress is compared. The expression of stress coefficient K is deduced by means of acoustic time method with fixed sound path, and the theoretical relationship between stress coefficient and sound path is given. The propagation law of critical refraction longitudinal wave is studied, and the propagation process is simulated by finite element method. The model is validated by comparing the measured value of X-ray stress analyzer with the stress simulation value of C-shaped specimen. In the third chapter, the theory of high-energy ultrasonic control of residual stress is studied. The mathematical expression of lattice dislocation relaxation induced by high-energy ultrasound is established. Secondly, the macroscopic plastic induction effect of high-energy ultrasound on materials is analyzed. The simulation and experiment of plastic induction prove that high-energy ultrasound can reduce the yield strength of materials, activate staggered atoms and accelerate the reduction of residual stress. The fourth chapter develops and establishes the software and hardware system of ultrasonic detection and control of residual stress. The different algorithm combinations of acoustic time difference measurement are simulated by MATLAB. Considering the uneven thickness of the coupling agent film and the error caused by the thickness of the measured parts, the acoustic time difference optimization algorithm is proposed. In the fifth chapter, based on the principle of residual stress acoustic elasticity testing, the calibration and calibration methods of the testing system are proposed, and the compensation theory and method of residual stress testing are emphatically studied. The theoretical model of the influence of measurement accuracy is proposed, and the temperature compensation algorithm is put forward and tested. The influence of crystal size and shape distribution on the measurement accuracy is studied, and the compensation methods of theoretical calculation and tensile test are put forward. Based on the principle of ultrasonic control of residual stress, three typical materials were used to study the influence of various factors on the stress control of different materials, and the optimal control parameters were obtained. In Chapter 6, the application of residual stress detection and control in aluminum alloy welding and riveting parts, structural steel welding parts and non-metallic parts was studied by using the developed ultrasonic residual stress detection and control system. Process specification and control process specification.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG115.28

【相似文献】